Environmental impact of nanotechnology

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The environmental impact of nanotechnology is the possible effects that the use of nanotechnological materials and devices will have on the environment. As nanotechnology is an emerging field, there is great debate regarding to what extent industrial and commercial use of nanomaterials will affect organisms and ecosystems.

Nanotechnology's environmental impact can be split into two aspects: the potential for nanotechnological innovations to help improve the environment, and the possibly novel type of pollution that nanotechnological materials might cause if released into the environment.

Nanopollution

Groups opposing the installation of nanotechnology laboratories in Grenoble, France, have spraypainted their opposition on a former fortress above the city

Nanopollution is a generic name for waste generated by nanodevices or during the nanomaterials manufacturing process. Ecotoxicological impacts of nanoparticles and the potential for bioaccumulation in plants and microorganisms is a subject of current research, as nanoparticles are considered to present novel environmental impacts. Of the US$710 million spent in 2002 by the U.S. government on nanotechnology research, $500,000 was spent on environmental impact assessments.

The capacity for nanoparticles to function as a transport mechanism also raises concern about the transport of heavy metals and other environmental contaminants. Two areas of concern can be identified. First, in their free form nanoparticles can be released into the air or water during production, or production accidents, or as waste by-product of production, and ultimately accumulate in the soil, water, or plant life. Second, in fixed form, where they are part of a manufactured substance or product, they will ultimately have to be recycled or disposed of as waste.

Scrinis[1] raises concerns about nano-pollution, and argues that it is not currently possible to “precisely predict or control the ecological impacts of the release of these nano-products into the environment.” A May 2007 Report to the UK Department for Environment, Food and Rural Affairs noted concerns about the toxicological impacts of nanoparticles in relation to both hazard and exposure. The report recommended comprehensive toxicological testing and independent performance tests of fuel additives. Risks have been identified by Uskokovic in 2007.[2] Concerns have also been raised about Silver Nano technology used by Samsung in a range of appliances such as washing machines and air purifiers.

Life cycle responsibility

To properly assess the health hazards of engineered nanoparticles the whole life cycle of these particles needs to be evaluated, including their fabrication, storage and distribution, application and potential abuse, and disposal. The impact on humans or the environment may vary at different stages of the life cycle.

The Royal Society report[3] identified a risk of nanoparticles or nanotubes being released during disposal, destruction and recycling, and recommended that “manufacturers of products that fall under extended producer responsibility regimes such as end-of-life regulations publish procedures outlining how these materials will be managed to minimize possible human and environmental exposure” (p.xiii). Reflecting the challenges for ensuring responsible life cycle regulation, the Institute for Food and Agricultural Standards has proposed standards for nanotechnology research and development should be integrated across consumer, worker and environmental standards. They also propose that NGOs and other citizen groups play a meaningful role in the development of these standards.

Environmental applications of nanotechnology

Main article: Green nanotechnology

Environmental remediation

Main article: Nanoremediation

Nanoremediation is the use of nanoparticles for environmental remediation.[4][5] Nanoremediation has been most widely used for groundwater treatment, with additional extensive research in wastewater treatment.[6][7][8][9] Nanoremediation has also been tested for soil and sediment cleanup.[10] Even more preliminary research is exploring the use of nanoparticles to remove toxic materials from gases.[11]

Some nanoremediation methods, particularly the use of nano zero-valent iron for groundwater cleanup, have been deployed at full-scale cleanup sites.[5] Nanoremediation is an emerging industry; by 2009, nanoremediation technologies had been documented in at least 44 cleanup sites around the world, predominantly in the United States.[6][12][13] During nanoremediation, a nanoparticle agent must be brought into contact with the target contaminant under conditions that allow a detoxifying or immobilizing reaction. This process typically involves a pump-and-treat process or in situ application. Other methods remain in research phases.

Water filtration

Main article: Nanofiltration

Nanofiltration is a relatively recent membrane filtration process used most often with low total dissolved solids water such as surface water and fresh groundwater, with the purpose of softening (polyvalent cation removal) and removal of disinfection by-product precursors such as natural organic matter and synthetic organic matter. [14] [15] Nanofiltration is also becoming more widely used in food processing applications such as dairy, for simultaneous concentration and partial (monovalent ion) demineralisation.

Nanofiltration is a membrane filtration based method that uses nanometer sized cylindrical through-pores that pass through the membrane at a 90°. Nanofiltration membranes have pore sizes from 1-10 Angstrom, smaller than that used in microfiltration and ultrafiltration, but just larger than that in reverse osmosis. Membranes used are predominantly created from polymer thin films. Materials that are commonly used include polyethylene terephthalate or metals such as aluminum.[16] Pore dimensions are controlled by pH, temperature and time during development with pore densities ranging from 1 to 106 pores per cm2. Membranes made from polyethylene terephthalate and other similar materials, are referred to as “track-etch” membranes, named after the way the pores on the membranes are made.[17] “Tracking” involves bombarding the polymer thin film with high energy particles. This results in making tracks that are chemically developed into the membrane, or “etched” into the membrane, which are the pores. Membranes created from metal such as alumina membranes, are made by electrochemically growing a thin layer of aluminum oxide from aluminum metal in an acidic medium.

Some water-treatment devices incorporating nanotechnology are already on the market, with more in development. Low-cost nanostructured separation membranes methods have been shown to be effective in producing potable water in a recent study.[18]

Energy

Research is underway to use nanomaterials for purposes including more efficient solar cells, practical fuel cells, and environmentally friendly batteries. The most advanced nanotechnology projects related to energy are: storage, conversion, manufacturing improvements by reducing materials and process rates, energy saving (by better thermal insulation for example), and enhanced renewable energy sources.

Research is ongoing to use nanowires and other nanostructured materials with the hope of to create cheaper and more efficient solar cells than are possible with conventional planar silicon solar cells.[19] Another example is the use of fuel cells powered by hydrogen, potentially using a catalyst consisting of carbon supported noble metal particles with diameters of 1-5 nm. Materials with small nanosized pores may be suitable for hydrogen storage. Nanotechnology may also find applications in batteries, where the use of nanomaterials may enable batteries with higher energy content or supercapacitors with a higher rate of recharging.

See also

References

  1. ↑ Gyorgy Scrinis (2007). "Nanotechnology and the Environment: The Nano-Atomic reconstruction of Nature". Chain Reaction 97: 23–26. Archived from the original on July 19, 2008.
  2. ↑ Vuk Uskokovic (2007). "Nanotechnologies: What we do not know". Technology in Society 29: 43–61. doi:10.1016/j.techsoc.2006.10.005.
  3. ↑ Royal Society and Royal Academy of Engineering (2004). "Nanoscience and nanotechnologies: opportunities and uncertainties". Retrieved 2008-05-18.
  4. ↑ Crane, R. A.; T. B. Scott (2012-04-15). "Nanoscale zero-valent iron: Future prospects for an emerging water treatment technology". Journal of Hazardous Materials. Nanotechnologies for the Treatment of Water, Air and Soil. 211–212: 112–125. doi:10.1016/j.jhazmat.2011.11.073. ISSN 0304-3894. Retrieved 2014-07-29.
  5. 1 2 U.S. EPA (2012-11-14). "Nanotechnologies for environmental cleanup". Retrieved 2014-07-29.
  6. 1 2 Mueller, Nicole C.; Jürgen Braun; Johannes Bruns; Miroslav Černík; Peter Rissing; David Rickerby; Bernd Nowack (2012-02-01). "Application of nanoscale zero valent iron (NZVI) for groundwater remediation in Europe". Environmental Science and Pollution Research 19 (2): 550–558. doi:10.1007/s11356-011-0576-3. ISSN 1614-7499. Retrieved 2013-11-21.
  7. ↑ U.S. EPA. "Remediation: Selected Sites Using or Testing Nanoparticles for Remediation". Retrieved 2014-07-29.
  8. ↑ Theron, J.; J. A. Walker; T. E. Cloete (2008-01-01). "Nanotechnology and Water Treatment: Applications and Emerging Opportunities". Critical Reviews in Microbiology 34 (1): 43–69. doi:10.1080/10408410701710442. ISSN 1040-841X. Retrieved 2014-07-29.
  9. ↑ Chong, Meng Nan; Bo Jin; Christopher W. K. Chow; Chris Saint (2010-05). "Recent developments in photocatalytic water treatment technology: A review". Water Research 44 (10): 2997–3027. doi:10.1016/j.watres.2010.02.039. ISSN 0043-1354. Retrieved 2014-07-29. Check date values in: |date= (help)
  10. ↑ Gomes, Helena I.; Celia Dias-Ferreira; Alexandra B. Ribeiro (2013-02-15). "Overview of in situ and ex situ remediation technologies for PCB-contaminated soils and sediments and obstacles for full-scale application". Science of The Total Environment. 445–446: 237–260. doi:10.1016/j.scitotenv.2012.11.098. ISSN 0048-9697. Retrieved 2014-07-29.
  11. ↑ Sánchez, Antoni; Sonia Recillas; Xavier Font; Eudald Casals; Edgar González; Víctor Puntes (2011-03). "Ecotoxicity of, and remediation with, engineered inorganic nanoparticles in the environment". TrAC Trends in Analytical Chemistry. Characterization, Analysis and Risks of Nanomaterials in Environmental and Food Samples II 30 (3): 507–516. doi:10.1016/j.trac.2010.11.011. ISSN 0165-9936. Retrieved 2014-07-29. Check date values in: |date= (help)
  12. ↑ Karn, Barbara; Todd Kuiken; Martha Otto (2009-12-01). "Nanotechnology and in Situ Remediation: A Review of the Benefits and Potential Risks". Environmental Health Perspectives 117 (12): 1823–1831. doi:10.1289/ehp.0900793. ISSN 0091-6765. JSTOR 30249860. Retrieved 2013-11-18.
  13. ↑ Project on Emerging Nanotechnologies. "Nanoremediation Map". Retrieved 2013-11-19.
  14. ↑ Raymond D. Letterman (ed.)(1999). "Water Quality and Treatment." 5th Ed. (New York: American Water Works Association and McGraw-Hill.) ISBN 0-07-001659-3.
  15. ↑ Dow Chemical Co. Nanofiltration Membranes and Applications
  16. ↑ Baker, L.A.; Martin (2007). "Nanotechnology in Biology and Medicine: Methods, Devices and Applications". Nanomedicine: Nanotechnology, Biology and Medicine 9: 1–24.
  17. ↑ Apel, P.Yu; et al. (2006). "Structure of Polycarbonate Track-Etch: Origin of the "Paradoxical" Pore Shape". Journal of Membrane Science 282 (1): 339–400.
  18. ↑ Hillie, Thembela; Hlophe, Mbhuti (2007). "Nanotechnology and the challenge of clean water". Nature Nanotechnology 2 (11): 663–664. Bibcode:2007NatNa...2..663H. doi:10.1038/nnano.2007.350. PMID 18654395.
  19. ↑ Tian, Bozhi; Zheng, Xiaolin; Kempa, Thomas J.; Fang, Ying;Yu, Nanfang; Yu, Guihua; Huang, Jinlin & Lieber, Charles M. (2007). "Coaxial silicon nanowires as solar cells and nanoelectronic power sources". Nature 449 (7164): 885–889. Bibcode:2007Natur.449..885T. doi:10.1038/nature06181. PMID 17943126. Cite uses deprecated parameter |coauthors= (help)

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